/*
	QMPlay2 is a video and audio player.
	Copyright (C) 2010-2017  Błażej Szczygieł

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Lesser General Public License as published
	by the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <PacketBuffer.hpp>

#include <cmath>

int PacketBuffer::backwardPackets;

bool PacketBuffer::seekTo(double seekPos, bool backward)
{
	const int count = packetsCount();
	if (count == 0)
		return false;

	const bool findBackwards = (m_pos > 0 && seekPos < at(m_pos - 1).ts);

	if (findBackwards && at(0).ts > seekPos)
	{
		if (floor(at(0).ts) > seekPos)
			return false; // No packets for backward seek
		seekPos = at(0).ts;
	}
	else if (!findBackwards && at(count - 1).ts < seekPos)
	{
		if (ceil(at(count - 1).ts) < seekPos)
			return false; // No packets for forward seek
		seekPos = at(count - 1).ts;
	}

	double durationToChange = 0.0;
	qint64 sizeToChange = 0;
	int tmpPos;

	const auto doSeek = [&](const int currPos, const bool forward, const bool keyFrame) {
		tmpPos = -1;
		if (forward)
		{
			for (int i = currPos; i < count; ++i)
			{
				const Packet &pkt = at(i);
				if (pkt.ts >= seekPos && (!keyFrame || pkt.hasKeyFrame))
				{
					tmpPos = i;
					return true;
				}
				else
				{
					durationToChange += pkt.duration;
					sizeToChange += pkt.size();
				}
			}
		}
		else for (int i = currPos - 1; i >= 0; --i)
		{
			const Packet &pkt = at(i);
			durationToChange -= pkt.duration;
			sizeToChange -= pkt.size();
			if (pkt.ts <= seekPos && (!keyFrame || pkt.hasKeyFrame))
			{
				tmpPos = i;
				return true;
			}
		}
		return false;
	};

	if (doSeek(m_pos, !findBackwards, false))
	{
		if (at(tmpPos).hasKeyFrame || doSeek(tmpPos, !backward, true))
		{
			m_remainingDuration -= durationToChange;
			m_backwardDuration += durationToChange;
			m_remainingBytes -= sizeToChange;
			m_backwardBytes += sizeToChange;

			m_pos = tmpPos;

			return true;
		}
	}

	return false;
}
void PacketBuffer::clear()
{
	lock();
	QList<Packet>::clear();
	m_remainingDuration = m_backwardDuration = 0.0;
	m_remainingBytes = m_backwardBytes = 0;
	m_pos = 0;
	unlock();
}

void PacketBuffer::put(const Packet &packet)
{
	lock();
	clearBackwards();
	append(packet);
	m_remainingBytes += packet.size();
	m_remainingDuration += packet.duration;
	unlock();
}
Packet PacketBuffer::fetch()
{
	const Packet &packet = at(m_pos++);
	m_remainingDuration -= packet.duration;
	m_backwardDuration += packet.duration;
	m_remainingBytes -= packet.size();
	m_backwardBytes += packet.size();
	return packet;
}

void PacketBuffer::clearBackwards()
{
	while (m_pos > backwardPackets)
	{
		const Packet &tmpPacket = first();
		m_backwardDuration -= tmpPacket.duration;
		m_backwardBytes -= tmpPacket.size();
		removeFirst();
		--m_pos;
	}
}
